Introduction of BJT, JFET and MOSFET

BJT (Bipolar Junction Transistor)

A BJT is a current controlled device (i.e. output characteristics of a device are controlled by base current and not by base voltage)

However in field effect transistor (FET) the output characteristics are controlled voltage (i.e. Electric field) and not by input current.

In BJT both holes and electrons play parts in conduction.

The input circuit of BJT is forward biased and hence has low input impedance. A BJT uses a current into its base to control a large current between collector and emitter. BJT gain is characterized by current gain.

A bipolar junction transistor is formed by joining three sections of semiconductors with alternative different doping. The middle section (base) is narrow and one of the other two regions (emitter) is heavily doped. The other region is called the collector.

 Two variants of BJT are possible: NPN (base is made of p-type material) and PNP (base is made of n-type material).

JFET (Junction Field Effect Transistor)

A JFET is a three terminal semiconductor device in which current conduction is by one type of carrier (i.e. electrons or holes). It is controlled by means of an electric field between the gate electrode and the conducting channel of the device. The JFET has high input impedance and low noise level. A JGET consists of a P-type or N-type silicon bar containing two PN junctions at eh sides. The bars form the conducting channel for the charge carriers. If the bar is of N- type it is called N- channel JFET and if the bar is P- type it is called a P- channel JFET. The two PN- junction forming diodes are connected internally and are taken out known as gate.

JFET has essentially three terminals.

Gate (G)                                              Source (S)                                           Drain (D)

Schematic symbol of JFET:

N- Channel JFET                                                                                                                P- channel JFET

In a JFET there is only one type of carrier:

                Hole in P- type channel

                Electron in N- type channel

For this reason it is also called unipolar transistor. As the input circuit of a JGET is reverse bias, the device has high input impedance. As the Gate is reverse bias, it carries very small current. JFET can also be said as voltage driven device. JFET use a voltage on gate terminal to control the current. JFET gain is characterized by the ratio of change in output current (drain current) to input voltage (gate voltage).

Working principle of JFET

When voltage (V_DS) is applied between drain and source terminal and voltage on gate is zero, the two PN-junctions at eh sides of the bar establish depletion layer. The electron will flow from source to drain through on channel between depletion layers.

When reverse voltage (V_GS) is applied between the gate and the source, the width of the depletion layer is increased; this reduces the width of conducting channel thereby increasing the resistance of N- type bar.

Importance of JFET

A JFET acts like a voltage controlled device (i.e. input voltage (V_GS) controls the output current. This is different from BJT where input current controls the output current. Thus JFET is a semiconductor device acting like vacuum tube.

Output characteristics of JFET

The curve between drain current (I_D) and drain source voltage of a JFET at constant gate source voltage (V_GS) is known as output characteristics of JFET.

The following points may be noted from this characteristic:

At first, the drain current (I_D) rises rapidly with drain source voltage (I_D) but then becomes constant. The drain source voltage above which drain current becomes constant is known as pinch off voltage.

After pinch off voltage, the channel width becomes so narrow that the depletion layer almost touches each other. The drain current passes through the small passage between these layers. Therefore increase in drain current is very small with (V_DS) above pinch off voltage. Consequently drain current remains constant.

The characteristic resemble that of a pentode valve.

Important terms in the analysis of JFET circuit

Short gate drain current (I_DSS): it is the drain current with source short-circuited to gate (i.e. voltage gate source (V_GS) = 0) and drain voltage (V_DS) equal to pinch off voltage. It is sometimes called zero bias current.

                Pinch off voltage: it is the minimum drain source voltage at which the drain current essentially becomes constant.

Gate source cut off voltage: it is the gate source voltage where the channel is completely cut off and the drain current becomes zero.

Application of JFET:

                As a buffer amplifier:

A buffer amplifier is a stage of amplification that isolates the preceding stage from the following stage. Because of the high input impedance and low output impedance, a JFET can act as an excellent buffer amplifier.

                As a phase shift oscillators:

               

As RF amplifier:

In communication electronics, we have to use JFET RF amplifier in a receiver instead of BJT amplifier because of following reasons:

                The nose level of JFET is very low than BJT.

                Since JFET is a voltage controlled device, is will well respond to low current signal provided by antenna.

• As Displacement sensors

• As High input impedance amplifiers

• As Low-noise amplifiers

• As Differential amplifiers

• As Constant current sources

• As Analogue switches or gates

• As Voltage controlled resistors              

Metal Oxide Semiconductor Field Effect Transistor (MOSFET)

Metal oxide semiconductor field effect transistor is an important semi-conductor device and is widely used in many circuit applications. The input impedance of a MOSFET is much more than that of JFET because of very small gate leakage current. The MOSFET can be used in any of the circuits covered for the JFET. Therefore, all the equations apply equally well to the MOSFET and JFET in amplifier connections.

The constructional details of N- channel MOSFET is similar to JFET except with the following modification:

                There is only a single P- region. This region is called substrate.

                A thin layer of metal oxide (usually silicon dioxide) is deposited over the left side of the channel. A metallic gate is deposited overt the oxide layer. As silicon dioxide is an insulator, therefore, gate is insulated from the channel. For this reason, MOSFET si sometimes called insulated gate FET.

                Like JFET, a MOSFET has three terminals (Source, Gate, and Drain)

Working principle of MOSFET

Instead of gate diode as in JFET, here gate is formed as a small capacitor. One plate of this capacitor is the gate and the other plate is the channel with metal oxide as the dielectric. When negative voltage is applied to the gate, electrons accumulate on it. These electrons repel the conduction band electrons in the N- channel. Therefore, lesser number of conduction electrons is made available for current conduction through the channel. The greater the negative voltage on the gate, the lesser is the current conduction from the source to drain. If the gate is given positive voltage, more electrons are made available in the N- channel, consequently, current from source to drain increases. The following points may be noted:

                In a MOSFET, the source to drain current is controlled by the electric field of capacitor formed at the gate.

                Unlike the JFET, and MOSFET has no gate diode. This makes it possible to operate the device with positive or negative gate voltage.

                As the gate forms the capacitor, therefore, negligible gate current flows whether positive or negative voltage is applied to the gate. Consequently, the input impedance of MOSFET is very high, ranging from 10,000 Mῼ to 10, 00,000 Mῼ.

Motivation

Motivation

Motivation is the word derived from the word “motive’ which means needs, desires, wants or drives within the individuals. It is the process of stimulating people to actions to accomplish the goals. In the work goal context the psychological factors stimulating the people’s behavior can be:

                Desire for money

                Success

                Recognition

                Job-satisfaction

                Teamwork etc

One of the most important function of management to create willingness amongst the employees to perform in the vest of their abilities. Therefore the role of a leader is to arouse interest in performance of employees in their jobs. The process of motivation consists of three stages:

                A felt need or drive

                A stimulus in which needs have to be aroused

When needs are satisfied, the satisfaction or accomplishment of goals.

Therefore, we can say that motivation is a psychological phenomenon which means needs and wants of the individuals have to be tackled by framing an incentive plan.

Importance of Motivation

Motivation is a very important for an organization because of the following benefits it provides:

·         Puts human resources into action

Every concern requires physical, financial and human resources to accomplish the goals. It is through motivation that the human resources can be utilized by making full use of it. This can be done by building willingness in employees to wor3.k. This will help the enterprise in securing best possible utilization of resources.

·         Improves level of efficiency of employees

The level of a subordinate or an employee does not only depend upon his qualification and abilities. For getting best of his work performance, the gap between ability and willingness has to be filled which helps in improving the level of performance of subordinates. This will result into:

                Increase in productivity

Reducing cost of operations, and

                 Improving overall efficiency

·         Leads to achievement of organizational goals

The goals of an enterprise can be achieved only when the following factors take place.

                There is best possible utilization of resources

                There is a co-operative work environment

The employees are goal-directed and they act in a purposive manner.

Goals can be achieved if co-ordination and co-operative takes place simultaneously which can be effectively done through motivation.

·         Builds friendly relationship

Motivation is an important factor which brings employees satisfaction. This can be done by keeping into mind and framing an incentive plan for the benefit of the employees. This could initiate the following things:

                Monetary and non-monetary incentives

Promotion opportunities for employees

Disincentives for inefficient employees

In order to build a cordial, friendly atmosphere in a concern, the above steps should be taken by a manager. This would help in:

                Effective co-operation which brings stability,

                Industrial dispute and unrest in employees will reduce

                The employees will be adaptable to the changes and there will be no resistance to the change

This will help in providing a smooth and sound concern in which individual interests will coincide with the organizational interests

This will result in profit maximization through increased productivity

·         Lead to stability of work force

Stability of work force is very important form the point of view of reputation and goodwill of a concern. The employees can remain loyal to the enterprise only when they have a feeling of participation in the management. The skills and efficiency of employees will always be of advantage to employees as well as employees. This will lead to a good public image in the market, which will attract competent and qualified people into a concern.

From the above discussion, we can say that motivation is an internal feeling which can be understood only by manger since he is in close contact with the employees. Needs, wants and desires are inter-related and they are the driving forces to act. These needs can be understood by the manger and he can frame to motivation plans accordingly. We can say that motivation therefore is a continuous process since motivation process is based on needs which are unlimited. The process has to be continued throughout.

We can summarize by saying that motivation is important both to an individual and a business. Motivation is important to an individual as:

                Motivation will help his achieve his personal goals

                If an individual is motivated, he will have job satisfaction

                Motivation will help in self-development of individual

An individual would always gain by working with a dynamic team

Similarly, motivation is important to a business as

                The more motivated the employees are, the more empowered the team is.

The more is the team work and individual employee contribution, more profitable and successful is the business

                During period of changes, there will be more adaptability and creativity

                Motivation will lead to an optimistic and challenging attitude at work place

Maslow’s Need Hierarchy Model

The needs have been classified into the following in order:

1.       Physiological needs: these are the basic needs of an individual which includes food, clothing, shelter, air, water, etc. These needs relate to the survival and maintenance of human life.

2.       Safety needs: These needs are also important for human beings. Everybody wants job security, protection against danger, safety of property, etc.

3.       Social needs: These needs emerge from society. A ma is a social animal. These needs become important. For example: love, affection, belongingness, friendship, conversation, etc.

4.       Esteem needs: These needs relate to desire for self-respect, recognition and respect form others

5.       Self-actualization needs: These are the needs of the highest order and these needs are found in those people whose previous four needs are satisfied. This will include need for social service, meditation.

Leadership

Leadership

Leadership is a process by which an executive can direct, guide and influence the behavior and work of others towards accomplishment of specific goals in a given situation. Leadership is the ability of a manager to induce the subordinates to work with confidence and zeal.

Leadership is the potential to influence behavior of other. It si also defined as the capacity to influence a group towards the realization of a goal. Leaders are required to develop future visions, and to motivate the organizational members to ant to achieve the visions.

Characteristics of leadership

1.       It is an inter-personal process in which a manager is into influencing and guiding workers towards attainment of goals.

2.       It denotes a few qualities to be present in a person who includes intelligence, maturity, and personality.

3.       It is a group process. It involves two or more people interacting with each other.

4.       A leader is involved in shaping and moulding the behavior of the group towards accomplishment of organizational goals.

5.       Leadership is situation bound. There is not best style of leadership. It all depends upon tackling with the situations.

Importance of leadership

1.       Initiates action: leader is a person who starts the work by communicating the policies and plans to the subordinate’s form where the work actually starts.

2.       Motivation: a leader proves to be playing an incentive role in the concern’s working. He motivates the employees with economic and non-economic rewards and thereby gets the work from the subordinates.

3.       Providing guidance: a leader has to not only supervise but also play a guiding role for the subordinates. Guidance here means instructing the subordinates the way they have to perform their work effectively and efficiently.

4.       Building morale: morale denotes willing co-operation of the employees towards their work and getting them into confidence and winning their trust. A leader can be a morale booster by achieving full co-operation so that they perform with best of their abilities as they work to achieve goals.

5.       Builds work environment: management is getting things done from people. An efficient work environment helps in sound and stable growth. Therefore, human relations should be kept into mind by a leader. He should have personal contacts with employees and should listen to their problems and solve them. He should treat employees on humanitarian terms.

6.       Co-ordination: co-ordination can be achieved through reconciling personal interests with organizational goals. This synchronization can be achieved through proper and effective co-ordinate which should be primary motive of a leader.

Decision making

Decision Making

Decision-making is an integral part of modern management. Essentially, rational or sound decision making is taken as primary function of management. Every manage takes hundreds and hundreds of decisions subconsciously or consciously making it as the key component in the role of a manager.

Decisions play important roles as they determine both organizational and managerial activities. A decision can be defined as a course of action purposely chosen from a set of alternative to achieve organizational or managerial objectives or goals. Decision making process is continuous and indispensable component of managing ay organization or business activities. Decisions are made to sustain the activities of all business and organizational functioning.

Decisions are made at every level of management to ensure organizational or business goals are achieve. Further the decisions make up one of core functional values that every organization adopts and implements to ensure optimum growth and drivability in terms of services and or products offered.

A lot of time is consumed while decisions are taken. In a management setting, decision cannot be taken abruptly. It should follow the steps such as

1.       Defining the problem

2.       Gathering information and collecting data Developing and weighing the options

3.       Choosing best possible option

4.       Plan and execute

5.       Take follow

Since decision making process follows the above sequential steps, a lot of time is spent in this process. This is the case with every decision taken to solve management and administrative problems in a business setting. Though the whole process is time consuming, the result of such process in a professional organization is magnanimous.

Process of decision making decision making process is like a school exam. Those who take good decision will pass the exam and the rest who does not take right decisions will have to bear the consequences. Being able to take good decision is important for everyone, whether he/she is a student, teacher, manager, principal, president, leader of any institution, etc. A student has to take decision about his career, a president has to take decisions regarding his country’s benefit, and a manager has to take decisions regarding his company and likewise the leader of any institution. So every single person has to pass this step in order to progress in their fields.

The meaning of decision in Latin is to ‘cut off’. This means that from all the available alternatives you choose one thing and then cut off from all the other alternatives. Due to this, the decision making process sometimes becomes very difficult. Choosing the right option from all the alternatives is very hard to do.

Decision making process requires thinking process, time, efforts, resources and also a little bit of knowledge and past experiences. Thinking process plays an important role in decision making process because it allows you to judge each and every thing. Timing is also important.

Taking right decisions on right time can save you from any trouble. Taking too little time to take decisions or taking too much time to execute your decision can cause many problems for you. Decision making processes also requires knowledge, experiences, and research. If you have knowledge, you can find out different alternatives for the problem faced. Making decisions without having proper knowledge about the problem can cause difficulties.

In our view decision making power is the key to progress in life. You might have seen many people who do not take proper decisions and then they have to suffer. On the other hand people who have this decision making power continues to progress in their life. Not all of us have this decision making power. We try to make right decisions but sometimes we make mistakes because we don’t know the steps that we should follow during the decision making process. So in order to take right decisions, it is important that we should know all the steps of decisions making process and follow them.

The decision making process involves the following steps:

1.       Curious observation

2.       Existence of problem

3.       Goals and planning

4.       Search, Explore & gather the Evidence

5.       Generate creative and logical alternative solutions

6.       Evaluate the evidence

7.       Make the educated guess (hypothesis)

8.       Challenge the hypothesis

9.       Reach a conclusion

10.   Suspend judgment

11.   Take action